1. Field of the Invention
The present invention relates to processes for the production of heat-retaining fiber which is characteristic of excellent effect of heat-retaining and good radiating capacity of far-infrared radiation, thereby the fabrics and non-woven fabrics made thereof are extensively applicable for cold-proof cloth or sportswear cloth to exhibit excellent effect of heat-retaining.
2. Description of the Related Art
Since ancient times, clothes provides human three major functions, body shading, heat-retaining, and beauty. As to the heat-retaining, conventional method is to increase the weaving density and thickness, to adopt multi-layer structure, and to add fleecy filling material between the inside and outside layer in order to reduce the heat loss due to transmission and convection. However, these methods make the resultant clothes so thick, heavy and cumbersome such that they are uncomfortable for the wearer.
Japanese Examined Patent Publication No. 58-10916 and Japanese Examined Patent Publication No. 58-136891 disclose a method of adhering vaporized metal onto the surface of cloth to increase the reflection of the cloth, thereby reducing the loss of body heat. Japanese Examined Patent Publication No.2-32364 discloses a method for mixing metal particles into the fiber to reflect heat radiation, thereby reducing the loss of body heat. The conventional art mentioned above has the following disadvantages. As to the method of adhering vaporized metal onto the surface of cloth, the adhered metal is easily stripped of during wearing and cleaning. Besides, the adhering of vaporized metal is batch operation, so the economic efficiency is low. As to the method of mixing metal particles into the fiber, in order to have the best effect of reflecting, the metal particles should adopt thin laminated metal powders having the average particle size of 1.about.100 .mu.m and the adding amount thereof should be 1.about.30%, therefore, in the processes of spinning and stretching, the pressure of spin pack assembly will rise very rapidly, situations of filament-flying and filament-breaking will increase, the production efficiency will go down. Besides, the metal particles in the fiber will make the heat-resistance and stability thereof worse.
It is also disclosed a method to obtain heat-retaining fiber by mixing ceramic powders having capacity of far-infrared radiation into fiber. Japanese Examined Patent Publication No. 2-160921 discloses far-infrared radiation ceramic powders selected from the group consisting of zirconium oxide, aluminum oxide, and magnesium oxide. Japanese Examined Patent Publication No. 2-259110 and Japanese Examined Patent Publication No. 1-314723 disclose far-infrared radiation ceramic powders consisting of silicon dioxide and titanium dioxide. Japanese Examined Patent Publication No. 63-182444 discloses far-infrared radiation ceramic powders selected from the group consisting of aluminum oxide, zirconium oxide, and magnesium oxide. Japanese Examined Patent Publication No. 63-126971 and Japanese Examined Patent Publication No. 63-92720 disclose far-infrared radiation ceramic powders selected from the group consisting of zirconium oxide, aluminum oxide, magnesium oxide (purity above 95%) and mixtures of two or more mentioned-above. British Patent Publication No. GB 2303375A discloses far-infrared radiation ceramic powders selected from the group consisting of zirconium oxide, zirconium silicate, silicon dioxide, and titanium dioxide. When the far-infrared radiation ceramic powders described above are heated, they can emit the far-infrared radiation which can be easily absorbed by human body and emitting efficiency thereof is very high. Therefore, they can absorb the body heat of human body after mixing into fibers and then emit the far-infrared radiation to warm the human body, thereby raising the effect of heat-retaining. Nevertheless, the efficiency of absorbing solar energy of the far-infrared radiation ceramic powders is not good, therefore, they can't efficiently convert solar energy into far-infrared radiation which can be easily absorbed by human body. Hence, the effectiveness of heat-retaining is still required to be further improved.
It is also provided with a method of mixing powders having capacity of adsorbing solar energy. Japanese Examined Patent Publication No. 1-132816 utilizes inorganic particles such as carborundum. Japanese Examined Patent Publication No. 4-257308 and Japanese Examined Patent Publication No. 1-314716 utilizes tin oxide particles doped with stibium oxide or other inorganic particles coated by this special-treated tin oxide. Although inorganic particles such as carborundum have good capacity of absorbing solar energy, while the color thereof is black, therefore the resultant fiber is also black and it is very difficult to be made into clothing with a variety of colors. Tin oxide particles doped with stibium oxide or other inorganic particles coated by this special-treated tin oxide have good capacity of absorbing solar energy and the color thereof is white, but the emitting efficiency of far-infrared radiation thereof is not good, therefore, they can't efficiently convert solar energy into far-infrared radiation which can be easily absorbed by human body. Hence, the methods mentioned above are still required to be further improved.